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NATURE HAPPENINGS - February 2005


Of Dabchicks and Hell-Divers
by Damian Fagan

From my vantage point, I scrutinize the usual suspects. Ring-necked ducks with their telltale white “spur” and green-winged teal with their buffy rump streaks loaf along the edges of the wetlands. Some mallards engage in aggressive mating behavior by chasing competitors away from prospective mates, while others doze in the comfort of the morning sun. A small group of wood ducks preen themselves, unconcerned with the activity around them. Dark American coots strut through my view, seemingly propelling themselves forward by their jutting head movements. But it is the loner floating along the edge of the bulrush that catches my attention.

The bird’s drab tawny-brown plumage is unremarkable compared to the colors flashed by the ring-necks and mallards. The bird is a bit smaller than the teal, but has a stouter bill that is white and wrapped with a black band towards the tip. With a sudden lunge forward, the bird is gone beneath the surface; barely a ripple betrays its presence.

Though one might confuse this bird with some of the diving ducks scattered across the pond, it is an unrelated species that shares this aquatic habitat. This bird is a member of the Grebe Family, of which there are 7 North American species.

Characteristics of the family are lobed toes with partial webbing between the toes (versus the webbed foot of a duck), generally slender bills with sawlike teeth along the edges, and legs set to the rear of the body. Though they tend to be weak fliers, these birds do migrate.

This particular species is the pied-billed grebe, named after its variegated or two-colored bill, but these birds are also known as “dabchicks” and “hell-divers”. Dabchick refers to the quick diving behavior while the hell-diver name originates from the bird’s ability to compress air out of their body cavity and between their feathers. This enables the bird to submerge like a submarine. At times, only the upper portion of their neck and head protrude above the water’s surface, and this behavior was once thought to have a “demonic” association.

Watching the activity of the bird, I can not see any fiendish indication from its behavior. The sporadic dives that the bird engages in are associated with feeding, as it searches for prey. Aquatic invertebrates, fish, crustaceans, tadpoles, frogs, and aquatic plants comprise the diet of the pied-billed. Studies of stomach contents reveal that these birds ingest a lot of feathers, presumably to coat the sharp edges of fish spines or frog parts, rather than for any nutritional value.

Pied-billed grebes spend the majority of their time on the water unlike the mallards that may forage in the uplands surrounding this marsh. When on land, grebes appear to have a difficult time walking because their legs are set very far back beneath their bodies. They seem ready to topple over, and because of this awkwardness, rarely spend much time away from their watery worlds. Larger relatives of the pied-billed, the Western and Clark’s grebes, are incapable of walking and it would take a modern miracle in structural engineering to enable them to stroll along the marsh’s edge.

This inability to walk on land should not be confused with the bird’s running start when they are ready to take to flight.

Grebes need a fairly long runway to get airborne, but constant wing-flapping compliments their running. Sometimes these birds mistake a rain-slickened roadway for a stream, but the birds can not lift off of the pavement because of the lack of the water’s buoyancy.

But this individual doesn’t have those concerns as the marsh has a good water level. The water inundates the thickets of bulrush and cattails, perfect locations for the grebe to construct its floating nest. Constructed of plant material woven together, the nest is anchored to submerged vegetation or to the bottom of the pond. Though they nest in sloughs or stagnant ponds, the birds don’t have to worry about their nests being washed away; however, they also don’t want it to be moved by the wind.

Since it is still early in the season, I don’t think this bird has an active nest. In another month, maybe, as the breeding season extends from March through September. At that time both parents will share in the incubation and chick-rearing, even to the point of giving their young a ride on the parent’s back. I’m surprised this piggyback behavior doesn’t translate into another common name for this reclusive, but widespread species.

 
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